After careful consideration, Republican U.S. Sen. Susan Collins of Maine says she will oppose the confirmation of Oklahoma Attorney General Scott Pruitt to lead the Environmental Protection Agency.

Collins tells Maine Public Radio she met at length with Pruitt and reviewed testimony from his confirmation hearing. She says he’s “an accomplished attorney with considerable knowledge about environmental laws,” and if he were nominated for another position in the federal government, Collins says she might support him.

But when it comes to the role and mission of the EPA, Collins says she and the nominee have very different visions.

“Specifically, I have significant concerns that Mr. Pruitt has actively opposed and sued the EPA on numerous issues that are of great importance to the state of Maine, including mercury controls for coal-fired power plants and efforts to reduce cross-state air pollution and greenhouse gas emissions,” she says. “His actions leave me with considerable doubts about whether his vision for the EPA is consistent with the agency’s critical mission to protect human health and the environment.”

Collins joins independent U.S. Sen. Angus King of Maine in her opposition to Pruitt as EPA administrator. In announcing his decision last month, King said there’s no record that he can find of Pruitt being “affirmative and strong” in enforcing environmental laws as attorney general.

“I just can’t, in good conscience, as somebody who’s taken seriously environmental protection all my life, approve the appointment of someone who is so manifestly opposed to the mission of the agency,” King said.

Pruitt has sued the EPA 14 times, and according to a letter from more than 400 former EPA workers last week, issued more than 50 press releases celebrating lawsuits to overturn EPA standards to limit mercury emissions from power plants, reduce smog and haze, clean up the Chesapeake Bay and control greenhouse gases.

Pruitt’s record, they wrote, “raises serious questions about whose interests he has served to date and whether he agrees with longstanding tenets of U.S. environmental law.”

During his Senate confirmation hearing, Pruitt was grilled over a series of letters he sent to federal agencies on state stationery that were critical of the economic effects of environmental rules, and drafted, almost word for word, by energy lobbyists. He has also been criticized as a climate change denier and someone who has indicated that he would like to see a limited role for the EPA.

For her part, Collins says she has not agreed with every regulatory action that EPA has issued, either.

“At times, I have found the agency difficult to work with,” she says.

But she says she is also worried about the potential for weakening a federal agency that works to implement and enforce landmark environmental laws such as the Clean Air Act, the Clean Water Act and the Clean Power Plan.

As an example, Collins points to Maine’s geographic location, near the end of what’s often described as the nation’s “air pollution tailpipe,” because it’s on the receiving end of pollution that’s generated by coal-fired power plants in other states. Reducing these air pollutants, Collins says, is important in a state like Maine, which has one of the highest rates of asthma in the country.

“And no matter what Maine does, unless we address the out-of-state sources of pollution, we cannot make the kind of progress that needs to be made,” she says.

Collins says another factor in her decision was the opposition to Pruitt expressed by the Friends of Acadia. With about 5,000 members around the country, the group wrote a letter to Collins about the need to reduce greenhouse gas emissions as a way to lessen the effects of climate change in Acadia National Park in Maine.

Stephanie Clement, conservation director for the friends’ group, says the effects of climate change are wide-ranging. For example, Acadia receives about five additional inches of rain on an annual basis than it did 100 years ago. Clement says there are also threats to the park’s infrastructure and to predator-prey relationships that could be affected by warming temperatures.

According to a 2016 survey by the Center for American Action, one-third of the members of Congress are skeptical that greenhouse gas emissions are driving climate change. Collins is not among them.

“I’ve talked to a lot of individuals throughout our state — scientists, environmental advocates, fishermen and boaters — and all of them are telling me of their concerns about how the environment is changing in our state,” she says. “And the changes we are already seeing in Casco Bay and the Gulf of Maine, for example, are cause for alarm.”

Both Collins and King’s offices have been inundated with calls and letters critical of Pruitt and other cabinet choices in recent weeks. Collins’ Portland office has also been the scene of several demonstrations against the EPA nominee.

At a recent Super Bowl-themed protest, Glenn Brand of the Sierra Club said he hoped Collins would vote against Pruitt.

“But we’re going to be here a lot,” he said. “Because there’s going to be opportunities for her to stand up for Maine repeatedly and show her true independence.”

Collins says she’s seeing bipartisan support for rolling back regulations that apply to coal-fired power plants, which she says is unfortunate since they are some of the most serious polluters.

“I reject the false choice of pitting the environment against the economy because for much of the state of Maine, the economy and the environment are inextricably linked,” she says.

"We are very excited that Sen. Collins and Sen. King have both announced their opposition to the confirmation of Scott Pruitt," says Lisa Pohlman, executive director of the Natural Resources Council of Maine. "We know that thousands of Mainers have called both of their offices and sent letters because there's really so much at stake here for Maine."

A vote to confirm Pruitt is expected later this week. Collins says in keeping with her past practice, regardless of which party is in the White House, she will vote for cloture on Pruitt’s nomination so that every member of the Senate can have a clear, up or down vote.